Abnormal keratinization is associated with the stratum corneum layer of the epidermis. The stratum corneum layer is composed of clear, dead squamous epithelial cells called corneocytes. Abnormal keratinization often appears as areas of scale-like buildup on the external skin surface and is the result of accumulated cell debris and dried keratohyalin from the cytoplasm of the dead, desquamated corneocyte cells.
The term "keratosis" is a microscopic term for describing the various ideological forms which contribute to abnormal skin keratinization such as "hyperkeratosis" which is hyperplasia of the stratum corneum seen with magnification. Whatever the ideology, the buildup of keratin is often undesirable, and a need exists in the art for an improved method of decreasing cohesion of corneocytes and promoting exfoliation of the cornified layers from the stratum corneum.
Topical compositions for treating skin disorders associated with disturbed keratinization are known. For example, U.S. Pat. Nos. 3,879,537, 4,105,783, 4,363,815, 5,258,391 and 5,385,938 describe the use of alpha-hydroxy acids and alpha-keto acids for treatment of a plethora of skin ailments including keratinization problems.
U.S. Pat. Nos. 4,386,104 and 5,385,943 describe the use of alpha, omega-n-alkane dicarboxylic acids with 7 to 13 carbon atoms and their physiologically acceptable forms to treat acne and keratoses such as presbyderma. U.S. Pat. No. 4,885,282 claims the use of mono- and di- carboxylic acids containing 4 to 18 carbons, their mercapto derivatives as well as salts and esters for treatment of ichthyosis with or without keratosis.
U.S. Pat. No. 4,973,473 teaches the use of a combination of carboxylic acid amides and a mucopolysaccharide as a moisturizer for treatment of dry skin. A topical composition, for treating dry skin, containing N-alkoxyalkylamides is described in U.S. Pat. No. 5,084,270; and U.S. Pat. No. 5,407,958 proposes the use of a composition containing an alpha-hydroxy acid neutralized with sodium hydroxy-methyl-glycinate to treat dry, rough skin.
The known art does not describe use of N-acyl-N,N',N'-ethylenediaminetriacetic acids (hereinafter also "NEDAT") and N-acyl-N,N',N'-(ethylenedioxy) diethylene- dinitrilotriacetic acids (hereinafter also "NEDENT") for prevention and treatment of abnormal skin keratinization, which the following description uniquely discloses.